EC MS

1. Hyphenated Technique of Capillary
Electrophoresis and Inductively Coupled
Plasma Mass spectrometry
Prepared By :
Mahendra G S
M-Pharm Pharmaceutical
Chemistry
JSSCP, MYSURU

2. • Introduction:
a. Elemental Speciation
b. Capillary Electrophoresis (CE)
c. Inductively Coupled Plasma Mass Spectrometry (ICP-MS)
• CE-ICP-MS Hyphenated System
a. CE-ICP-MS Instrument Setup
b. Interface and Modified Nebulizer Design
c. Direct Injection Interface design
d. Pulsed Field Capillary Electrophoresis
e. Laminar Flow Effect
• Elemental Speciation Analysis application
a. Chemical forms of As and Cr in preservative wood
b. Leaching effect of As and Cr in surround soil
• Preliminary Results
Outline

3. Elemental Speciation
• Elemental Speciation is the identification and
quantification of the chemical form of an
element.
• The toxicological, physiological and biological
effects are species dependent.
• Main area:
---Environmental area
---Food area
---Health area

4. Capillary Electrophoresis (CE)
• Separate mixture of ionic
species quickly
• Good resolution and
separation efficiency
• Simple instrument set-up
• Relative low cost
• Require much less sample

5. Inductively Coupled Plasma Mass
spectrometry (ICP-MS)
• Direct element information
and quantification
• Species identification via
migration time
• Low detection limit
• High sensitivity and
selectively

6. CE-ICP-MS Instrument Setup
Quadrupole Mass Analyzer
Detector
Computer
ICP
Interface
UV Detector
Buffer / SampleMake-up Solution
Capillary
CE HV Power Supply

7. ICP Nebulizer
Flow From
CE Capillary
CE Platinum Ground Electrode
Make-up Sheath Flow
O-ring
The CE-ICP-MS Interface
Requirements:
An electrical connection to the end of CE capillary
High aerosol transport efficiency
Low dead volume

8. Nebulizer Gas In
CE Capillary
Stainless Steel Tube
To Spray Chamber
CE Capillary
Stainless Steel Tube
Nebulizer Inner Tube
The Modified Concentric Nebulizer

9. The Concentric Nebulizer and Interface
• Advantages:
- Universally applicable
- Easy to install and remove
- Inexpensive
• Disadvantages:
- Sample solution from CE is diluted and causes losses in
sensitivity.
- Increase sample solution flow rate may decrease CE
resolution.
- Decrease make-up sheath flow rate may decrease ICP-
MS aerosol transfer efficiency

10. Nebulizer Gas
Platinum Electrode
CE Capillary
Nebulizer Body
ICP Torch
Sampler Cone
The Direct Injection Interface

11. The Direct Injection Interface
• Advantages:
- Improve precision.
- Reduce rinse-out time.
- Low absolute detection limit.
- Reduce peak broadening due to the low dead volume.
• Disadvantages:
- ICP-MS plasma may be extinguished.
- High cost.
- Difficult to use.

12. V
A
Sample or Buffer
UV Detector
Current
Voltage Probe
Pulse Power Supply
Capillary
Interface
Nebulizer
To ICP
Capillary with Silver Paint
+G
Pulsed Field CE-ICP-MS Instrument Setup

13. Continuous ms or ms,
Pulsed
DC
20kV, 40mA
0.8W
Dc: 5kV, 10mA (0.05W)
Pulse: 100kV, 0.2mA,
100ms, 200Hz (20W)
Average: 0.45W
t1
t2
Pulse
DC
Pulsed Field CE-ICP-MS
Comparison of power consideration for a
continuous versus pulsed CE

14. Pulsed Field CE-ICP-MS
• Theoretical plate number N=L2/L
2=(mep+meo)V/2D (1)
• Resolution Rs= N1/2 (v /) /4 (2)
• Plate Height Hheating =(2S2m2/2D)((K1E5rc
6/mapp)
+ (K2 E6 rc
6/LD)) (3)
Where V is the applied voltage, E is the electric field strength.
1. Kennedy, R. T.; German, I.; Thompson, J. E.; Witowski, S. R. Chem. Rev. 1999,
99, 3081-3131.
The effect of Joule heating on band broadening

15. Pulsed Field CE-ICP-MS
• Advantages:
- Reduce the Joule heating which causes
band broadening in conventional CE.
- Large diameter capillary can be used to
attain high flow rate.
- The interface is simpler and high
sensitivity without dilution of the analyte.
• Disadvantages:
- High cost.

16. Cross-Sectional Flow Profile Due to Electroosmotic Flow
Cross-Sectional Flow Profile Due to Laminar Flow
Laminar Flow Effect in CE-ICP-MS

17. Elemental Speciation Analysis Application
Major consideration:
• The toxicity of copper (Cu), chromium (Cr) and
arsenic (As) is dependent on elemental species.
• Preservative wood and soil sample Preparation.
•The state of As and Cr on treated wood.
•The effect of pH on leaching of As and Cr.
•As and Cr leach from the treated wood into soil.
The most widely used wood preservative is chromated
copper arsenate (CCA)

18. Preliminary Result
The concentric nebulizer and interface

19. Design 1
Design 2
Design 3
Design 4
CE liquid flow
Make-up buffer
Torr seal
The Configuration of Nebulizer Tip

20. 0.E+00
1.E+05
2.E+05
3.E+05
4.E+05
5.E+05
6.E+05
7.E+05
8.E+05
9.E+05
1.E+06
0.500 0.600 0.700 0.800 0.900 1.000 1.100 1.200
Modified Nebulizer gas flow rate (L/min)
1ppmInsignal(acps)
Modified Nebulizer Gas Flow Rate Effect

21. 0.0E+00
5.0E+05
1.0E+06
1.5E+06
2.0E+06
2.5E+06
3.0E+06
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50
Make-up sheath flow rate (mL/min)
1ppmInsignal(acps)/solutionflowrate(mL/min)
Make-up Sheath Flow Rate Effect